### Jibber Jabber
The human ear has a large dynamic range in sound reception. The ratio of the sound intensity that causes permanent damage during short exposure to that of the quietest sound that the ear can hear is greater than or equal to 1 trillion (10^{12}). Such large measurement ranges are conveniently expressed in logarithmic scale: the base-10 logarithm of 10^{12} is 12, which is expressed as a sound pressure level of 120 dB re 20 μPa.

16bitをダイナミックレンジに換算すると「2の16乗」で96dBですが、96.1dBでもアウトなので、ふつうは12dBの余裕を持たせます。音楽の場合、演奏のたびに最大音量が10dBくらい上下する可能性があるからです。つまり、16bitで録音した場合、実効的なダイナミックレンジは70dB少々です。

$$L=log_{10}{(\text{Power ratio})}=log_{10}{(\text{Amplitude ratio})^{2}}$$

$$10*log_{10}(2^{16})^{2}=96\text{dB}$$

### 使用iphone录音
{{youtube>UhJXaqFJF4E}}
<wrap lo>使用iphone的拍摄的视频。很容易有音量超出</wrap>

[iPhone的录音能力](https://sound.stackexchange.com/questions/15226/what-is-the-maximum-sample-rate-bit-depth-of-the-iphone-for-recording)

48kHz, 16-bit Mono (or Stereo if you have a plug-in mic of some sort which supports Stereo).

<wrap lo>参考资料：  
 * 自然音を録音したいのですが https://oshiete.goo.ne.jp/qa/7636800.html
</wrap>